Turkish Neurosurgery 2006 , Vol 16 , Num 3
Investigation with the Oxidative Stress Theory (The Free Radical Theory) of Aging Neurobiology in the Experimental Spinal Cord Trauma Model: A Biochemical Study
Gökhan BOZKURT1,2, Selçuk PALAOĞLU2, Kamer KILINÇ3, Mürvet TUNCEL4, Özden PALAOĞLU6, İlker ETİKAN5
1Hacettepe University, Institute of Neurological Sciences and Psychiatry School of Medicine Ankara, Turkey
2Hacettepe University, Departments of Neurosurgery, Ankara, Turkey
3Hacettepe University, Departments of Biochemistry , Ankara, Turkey
4Hacettepe University, Departments of Anatomy, Ankara, Turkey
5Hacettepe University, Departments of Biostatistics, Ankara, Turkey
6Ankara University, School of Medicine, Departments of Pharmacology, Ankara, Turkey
OBJECTIVE: Aging, expressing postmaturational changes, is a process that contains a decline in the organism's simultaneous and harmonic response, adaptation potential, and resistance ability to external and negative events (stressors and stimuli). The free radical theory of aging puts forward that aging and its accompanying diseases are the results of reactions between reactive free radicals and biomolecules. There is a high correlation between the hydroxyl radical forming rate and aging. Since pineal melatonin secretion decreases with aging, the toxic effects of free radicals are expected to increase secondary to decreased melatonin secretion. The pineal melatonin, also called the anti-aging hormone, attenuates hydroxyl radical-induced neuronal damage. The objective of our study was to create an experimental model for the free radical theory of aging in spinal cord trauma and to confirm lipid peroxidation levels in young and aging spinal cord segments after spinal cord trauma.

MATERIALS AND METHODS: In this study following experimental spinal cord trauma, the extent of oxidative neuronal injury was measured among different age groups in order to show its relation with aging. For this trial young (n:14, 3 months old, 80-110 gr), old (n:14, 18-22 months old, 350-450 gr, naturally aged) and pinealectomised albino-rats (n:14, 3 months old, 4 months wait, 80- 110 g, artificially aged) were used. Lipid peroxidation was measured in all spinal cord segments obtained in every group of experiments.

RESULTS: Lipid peroxidation levels of both naturally and artificially aged groups were significantly higher than the group of young rats. There was no statistically significant difference between naturally aged and artificially aged groups. Lipid peroxidation levels increased during aging in the spinal cord of the animals.

CONCLUSIONS: One of the most important theories on the cause of spinal cord aging is the free radical mechanism. Pineal gland functions decrease by aging. Decreased melatonin function, decreased antioxidant capacity, and accumulation of hydroxyl radicals are the chief determinants of aging. It is necessary to carry out many studies on spinal cord aging especially regarding the long-term effects of the pineal gland and melatonin as they may be important agents for the recovery of spinal cord injury Keywords : aging, free radical theory, melatonin, pineal gland, pinealectomy, spinal cord trauma

Corresponding author : Gökhan Bozkurt, gbozkurt@hacettepe.edu.tr